Speaker
Description
The cosmological principle — the foundational axiom that defines modern cosmology — states that the universe is homogeneous and isotropic on large scales. But this assumption, while elegant, must be tested. Recent observations — including the Hubble tension and our unexplained local bulk motion relative to the Cosmic Microwave Background — suggest that the nearby universe may contain structure significant enough to challenge this principle. While these questions have traditionally been approached using high-redshift data, the local universe (
In this project, we use the galaxy luminosity function as a tool to study the distribution of starlight — or luminosity density — across the sky. This provides insight into the underlying mass distribution and whether it aligns with the predictions of a homogeneous universe. Using data from the 6dF Galaxy Survey, 2MASS Redshift Survey, and GAMA, we divide the sky into hundreds of distinct regions and apply a Bayesian hierarchical model to estimate the luminosity function parameters in each region. This approach allows us to capture both local variations and their relation to a global cosmic average.
From this, we construct a 3D map of the stellar luminosity density across the Local Volume (out to
